Listed below are a number of parameters of interest in gamma-ray spectroscopy us

Question

Listed below are a number of parameters of interest in gamma-ray spectroscopy using scintillation detectors: a. Density of the detector medium b. Kinetic energy required to create a scintillation photo in the crystal c. Average atomic number of the detector medium d. Geometry of the source-detector system e. Gain of the photomultiplier tube f. Quantum efficiency of the photocathode in the photomultiplier g. Gain of the amplifier used between the detector and pulse analysis system h. Fraction of light generated in the crystal that reaches the photocathode of the PM tube (light collection efficiency) Identify those parameters from this list that have a major influence on the detector intrinsic peak efficiency. Repeat, but now identify those that have a major influence on energy resolution.

Explanation / Answer

1) Detector intrinsic peak efficiency means: the probability that an emitted gamma ray will interact with the detector and produce a count. The bigger the detector, the larger the efficiency. Shielding property of the material in detector is also an important factor. So,
a) Density of detector medium will matter (related to shielding effect)
d) Geometry of source detector will matter such as whether detector is huge.
e) Gain in PM. (This gives a nice peak)
h) Fraction of light generated in the crystal that reaches the photocathode of the PM tube (light collection efficiency)

2) Energy resolution
This means how well different energies which are only slightly separated can be detected clearly.
b) Kinetic energy to create scintillation (May create a dopplar shift which affects energy resolution)
c) Average atomic number (in terms of the energy levels for different atoms)
f) Quantum efficiency of photocathode in PM (It tells about the number of carriers detected per energy level. A better quantum efficiency means better resolution)
g) Gain of amplifier between detector and pulse analysis system. This works as amplifier, which can be good for resolution.

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